Equipment Operator, these troubles are easy todetect without too much checking and testing. Thesupervisor must, however, make the mechanicsaware that there probably was, in addition, anactual or contributing cause to the power failure.The supervisor must train the mechanics to lookfor this cause while making repairs. Unlesseliminated, this may be the cause of major troublelater on.Too often, troubles concerned with power lossoccur within the engine and are not easily found.It is these hard-to-find troubles, with little or novisual indication, that keep the CMs busy. Anoperator may notice a decided power loss in theequipment and, because there is excessive smokecoming from the exhaust, report the trouble asimproper carburetion, or, in the case of a dieselengine, as injector trouble.An inexperienced mechanic may notice anincreased engine temperature in addition to theexhaust smoke and diagnose the loss of power asimproper valve action or as trouble in the coolingsystem. The diagnoses are comparatively simplethrough visual indications. But, as a CM1, youknow that there are many causes of power lossthat have little or no visual indications. Examplesare incorrect ignition timing, faulty coil orcondenser, defective mechanical or vacuum sparkadvance, worn distributor cam, or slipping clutch.Any of them can cause a power loss.After a deficiency has been located in anengine, it is usually easy to make the necessarycorrections to eliminate the conditions causing thedeficiency. Careful analysis and straight thinking,however, are often needed to find the cause ofengine deficiencies. If a supervisor has a thoroughknowledge of the basic engineering and operatingprinciples of an engine, his or her job of trainingthe mechanics will be easier and more interesting.In diagnosing engine deficiencies, the supervisormust never jump to conclusions and make adecision on the nature of repairs to be madebefore being sure that what will be done willeliminate the trouble. The mechanics mustbe able to interpret the engine instrumentindications as well as use the proper testingdevices. Furthermore, they must be able to roadtest the equipment to determine whether repairshave been made satisfactorily and whether a partor several parts should be adjusted or replaced.Besides, the mechanic must know when and howto make emergency adjustments for every unit onthe engine.It may seemrequired of athat some of the qualificationsgood mechanic point to theknow-how of an automotive engineer. However,no one person can know all about engines andalso be an expert in repairing all kinds of poweredequipment used by the SEABEEs. For instance,if the checks or instrument tests indicate someinternal trouble in a magneto, carburetor, or fuelinjection unit, the repairs should be made bymechanics who have experience or have beenspecially trained to use the equipment to do theparticular job at hand. It is the supervisor whowill be expected to have the answers to allthe questions asked by less experienced me-chanics.The three basic factors that affect an internalcombustion engines power are as follows:COMPRESSION, IGNITION, and CARBURE-TION. In the diesel engine, fuel is injected intoeach cylinder, and ignition depends on the heatof compression; in the gasoline engine, ignitionand carburetion are independent. In both engines,of course, proper action and timing of all threefactors are necessary for the engine to produceits rated power.It is obvious then that an engine runs anddevelops rated power only if all of its partsfunction or operate as they should. If any of theseparts wear or break, requiring replacement oradjustment, the performance charts and enginespecifications are tools that will help themechanic to bring those parts back to theiroriginal relationship to each other.There are more factors NOT directlyassociated with engine working parts that mustbe considered in correcting engine powerlosses.OPERATING CONDITIONS can affect en-gine power. For example, the usable horsepowerof an engine is reduced by the number ofaccessories it must operate. If the engine isrequired to provide power for lifting operationsat the same time it is delivering power to wheelsor tracks, the engine may be overloaded andmay not be able to develop its rated rpm; con-sequently, the rated horsepower would NOT bereached.The effect of ALTITUDE on engine powermust also be considered. As a rule, 2 1/2 percentof the output of an engine is lost for every1,000-foot increase in elevation above sea level.Overheated air entering the cylinders has the sameeffect on engine power as an increase in altitude.In computing horsepower output, engineers willdeduct as much as 1 percent for each 10°F risein the intake air temperature above a normaltemperature of 70°F.3-9